MUMBAI, India – The triple bombing that killed 17 in the heart of India’s financial capital sparked anger Thursday over the government’s inability to prevent terror strikes despite overhauling security forces after the 2008 Mumbai siege.

Indian officials say they have made extraordinary security reforms since 10 Pakistani terrorists rampaged across the city nearly three years ago, but following Wednesday’s attack they warned they may never be able to guarantee a terror-free nation in a region plagued by extremism.

“We live in the most troubled neighborhood in the world,” said Indian Home Minister Palaniappan Chidambaram, pointing to nearby Pakistan and Afghanistan. “Every part of India is vulnerable.”

No terror group claimed responsibility — and investigators had no immediate suspects — in the bombings that shook three separate neighborhoods within minutes during Wednesday’s busy evening rush.

Chidambaram said the government had no intelligence warning. “Whoever has perpetrated this attack has worked in a very, very clandestine manner,” he said.

Prime Minister Manmohan Singh, who flew to Mumbai to meet with the victims, called on authorities “to relentlessly pursue the perpetrators. They must be brought to justice quickly.”

“I assure the people that the government will do everything in its power to prevent such attacks in the future,” he said.

But many remained frustrated.

“Why is Mumbai being attacked again?” said Uttam Jain, who works in the Jhaveri Bazaar market that was hit by one of the blasts. Jain said he was “disgusted with politicians who promise security, but do nothing after the media cameras are gone.”

The bombings marked the worst terror attack in India since the 2008 siege, which killed 166 people over three days.

After that attack, the government expanded police recruiting and training, bought high-tech equipment and updated its arsenal. It established a National Investigation Agency to probe attacks and set up commando bases — including one in Mumbai — to react rapidly to them.

Ajai Sahni, executive director of the Institute for Conflict Management, called the NIA “a tiny little organization” with few resources. “It is not the FBI.”